Wave soldering apparatus having unobstructed work piece path

ABSTRACT

The wave soldering apparatus of present disclosure includes a sump for receipt of a predetermined level of molten solder and having a driveshaft-receiving opening in the bottom wall thereof. A fountain is disposed in such sump and is formed with a chamber that leads upwardly above the predetermined level and terminates in a horizontally disposed outlet orifice. Molten solder is pumped into the lower portion of such fountain by pump means which includes an impeller having a driveshaft projecting therefrom and through the driveshaft-receiving opening. Barrier means surrounds such driveshaft means to block molten solder from coming into contact therewith and leaking out through the driveshaft-receiving opening.

United States Patent 1 Fitzsimmons Nov. 20, 1973 [75] Inventor: RobertD. Fitzsimmons, Windham,

N.l-l.

[73] Assignee: Gale Systems, Inc., Andover, Mass.

[22] Filed: Feb. 24, 1972 [21] Appl. N0.: 228,812

l-lepner 29/503 X Elliott et a1. 228/37 X Primary Examiner-J. SpencerOverholser Assistant Examiner-Robert J Craig AttorneyVem Schooley [5 7]ABSTRACT The wave soldering apparatus of present disclosure includes asump for receipt of a predetermined level of molten solder and having adriveshaft-receiving opening in the bottom wall thereof. A fountain isdisposed in such sump and is formed with a chamber that leads upwardlyabove the predetermined level and terminates in a horizontally disposedoutlet orifice. Molten solder is pumped into the lower portion of suchfountain by pump means which includes an impeller having a driveshaftprojecting therefrom and through the driveshaft-receiving opening.Barrier means surrounds such driveshaft means to block molten solderfrom coming into contact therewith and leaking out through thedriveshaft-receiving opening.

7 Claims, 5 Drawing Figures PATENTED NOV 20 \973 SHEET 10F 2 INVENTOR.05527 0. firzs/MMa/vs J J g5 M W flrraeA/eys PATENTED um 20 I975 SHEET 2OF '2 FIGA ' INVENTOR. ROBERT 'D. firzs/M/wo/vs WAVE SOLDERING APPARATUSHAVING UNOBSTRUCTED WORK PIECE PATH BACKGROUND OF THE INVENTION 1. Fieldof the Invention The present invention relates to a soldering device forpumping molten solder upwardly through a fountain to create a standingwave of molten solder for having components passed into contacttherewith for soldering thereof.

2. Description of the Prior Art Numerous wave soldering devices havebeen proposed for producing a standing molten solder wave for enablingelectrical components to be passed therethrough. However, most of suchprior art devices include a horizontally disposed pump impeller disposedin the bottom of the sump and having a driveshaft projecting upwardlytherefrom to connect with a drive motor disposed above the surface ofthe hot molten solder. Such devices suffer the shortcoming that thedrive mechanisms are located above the sumps and obstruct the freedom toapproach horizontally with a conveyor the orifice from all directionsand also obstruct the activities of workmen working with such devices.

Other wave soldering devices have been proposed which include a solderpump having a driveshaft projecting through the wall of the sump, butdifficulty is encountered in attempting to seal such driveshafts in amanner that will hold up under the extremely hot temperatures requiredto maintain the solder in its molten state. A wave soldering apparatusof this type is shown in US. Pat. No. 3,092,059. Applicant is also awareof the following US. Patents:

3,277,566 Christensen 3,266,l 36 Gutbier 3,430,332 Roczey-Koller3,056,370 Barnes 3,082,520 I-lepner 3,004,505 Dvorak 3,037,274 Hancock3,100,471 Gutbier SUMMARY OF THE INVENTION The soldering apparatus ofthe present invention is characterized by a pump submerged in the soldersump and having a driveshaft projecting through the sump wall andsurrounded by a barrier to block solder from impinging on suchdriveshaft and leaking out therearound.

The objects and advantages of the present invention will become apparentfrom a consideration of the following detailed description when taken inconjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a wavesoldering apparatus of present inven-tion with a work piece carryingconveyor extending thereover;

FIG. 2 is a vertical sectional view. in enlarged scale, taken along theline 2-2 of FIG. 1;

FIG. 3 is a vertical sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a vertical sectional view, in enlarged scale, taken along theline 4-4 of FIG. 2; and

FIG. 5 is a horizontal sectional view taken along the line 5-5 of FIG.4.

DESCRIPTION OF THE PREFERRED EMBODIMENT 0 a horizontally disposedimpeller 19 (FIG. 4) driven by an upwardly extending drive pipe 21 whichis connected on its upper end with a co-axial driveshaft 23 whichprojects downwardly through the bottom wall of the sump 11 and has adriven pulley 25 on its lower extremity. An upstanding barrier tube 27projects upwardly from the bottom wall of the sump 1 1 and is telescopedbetween the driveshaft 23 and drive pipe 21 to block molten solder fromcontacting the driveshaft 23 and leaking out around such driveshaft.Consequently, the driveshaft 23 may be driven from the bottom endthereof to drive the impeller 19 and pump molten solder into the lowerportion of the fountain 13 to force such molten solder upwardly in suchfountain to flow out the horizontal orifice 15 and form a standing wave16 thereover for having work pieces 18 (FIG. 1) brought into contacttherewith for soldering thereof. Since the pump 17 is driven from thebottom side of the sump 11, there is no requirement for disposing adrive motor above such sump and, consequently, the area above such sump11 is left unobstructed to enable a conveyor, generally designated 31,(FIG. 1) to be placed over such wave 16 for carrying work pieces 18(FIG. 1) into contact with such wave 16, and the activity of workmentworking with such pieces will not be obstructed by a drive mechanism,nor will the freedom to approach orifice 15 from any horizontaldirection by a conveyor 31 be obstructed by any drive mechanism.

Referring to FIG. 3, the sump 11 is supported in a cabinet, generallydesignated 35, and is formed in transverse cross section with side wallsthat define a reduced-in-cross section lower portion 37 that flaresoutwardly to form an enlarged upper portion 39. The sump 11 is insulatedby means of insulation 41 and has heaters 42 and 43 mounted along thesides thereof for heating the molten solder.

Still referring to FIG. 3, the fountain 13 includes a pair of upwardlyand inwardly angled side walls 47 and 49 and a pair of upright end walls51 and 53 (FlG.2) which project slightly above the upper edge of theside walls 47 and 49 to direct the spill from the solder wave 16 to thesides of the fountain l3 and prevent spillage thereof over the end wallsof such fountain. A series of horizontal baffles 57 are disposed in theupper portion of the fountain 13 to baffle the solder flow and maintaina uniform wave 16. A series of'vertical baffles 59 are also provided forassisting in maintaining uniform flow.

Referring to FIG. 2, the fountain end wall 53 is formed in its lowerextremity with a through bore 61 for receipt of a pump outlet fitting 63that directs flow to the center of the fountain 13.

Referring to FIGS. 4 and 5, the pump 17 includes a housing which isformed with a vertically extending through central passage for receivingthe barrier tube 27 and which forms a bottom inlet 67 and top inlet 69.Referring to FIG. 5, the housing 17 is formed with a horizontallyextending impeller chamber 71 that re- 3 ceives the impeller 19 and suchimpeller also includes a through central passage 72 (FIGA) which has thelower end of the drive pipe 21 received therein and welded thereto. Thebarrier tube 27 is telescoped upwardly inside the drive pipe 21 and hasits lower end projecting through an opening 75 in the bottom wall of thesump 11 and welded to such wall. Bearings 77 are received in the upperand lower extremities of the barrier tube 27 for receipt of thedriveshaft 23. The upper end of the driveshaft 23 is coupled to theupper end of the drive pipe ,21 by means of a coupling unit 81.

Referring to FIG. 2, a vertically extending drive motor 85 is mounted tothe cabinet structure 35 with its driveshaft projecting downwardly andcarrying a drive pulley 87 which is coupled with the driven pulley 25 bymeans of a V-belt 89.

Referring to FIGS. 1 and 2 in operation, the circuit boards or the liketo be soldered are placed on the conveyor 31 which has one end extendingover the top of the sump 11. Disposed under the opposite end of suchconveyor 31 are a fluxer 91 and preheater 93.

Solder is placed in the sump 11 to a level 98 (FIG. 2) below the top ofthe drive pipe 21 and the temperature control knob 95 (FIG. 1) turned tothe desired temperature to energize the heaters 42 and 43 (FIG.3) andmaintain the solder at the desired temperature. It is common practice tofloat a layer of oil compound 97 on top of the solder for isolating suchsolder from the air to prevent oxidation thereof and consequentformation of a film or dross thereon. Further, the oil compound 97 ismixed with the solder as it flows from the fountain 13 to provide adesired ratio of oil compound to solder in the wave 16 and to facilitatesoldering of the work pieces. This feature is more fully explained in myU. S. Pat. No. 3,589, 590.

Referring to FIGS. 1, 2 and 4 the pump control knob 99 (FIG.1) is thenturned to actuate the motor 85 and the desired pump rate is dialed torotate the driveshaft 23 and consequently, the drive pipe 21 to rotatethe impeller 19 and commence pumping of solder out the directional pumpoutlet 63 and into the fountain 13. The molten solder and oil compoundmixture passing upwardly in the fountain 13 passes out through theorifice to produce a smooth wave 16 and the work pieces 18 are broughtinto contact with such wave for soldering thereof. 1

Referring to FIGS. 2 and 5(as described in US. Pat. No. 3,589,590) byincreasing the speed of the pump 17, the flow rate spilling from thewave 16 will be increased thereby drawing greater quantities of oilcompound 97 with the solder moving downwardly through the molten solderand into the inlets 67 and 69 of the pump 17 to increase the ratio ofoil compound to solder in the fountain and, consequently, in the wave16. It has been found that the provision of the inlet 69 on the top sideof the pump 17 for direct receipt of oil compound 97 passing downwardlyfrom the top surface of the solder and location of the inlet 67 on thebottom side of the pump 17 to somewhat isolate such inlet from directcommunication with the downwardly moving solder provides the desiredratio of oil compound to solder in the normal operating ranges.

It is particularly important that the pump 17 is driven from the bottomside of the sump 11 thereby enabling 6 the conveyor 31 (FIGJ) to beplaced approaching from any horizontal direction directly over thefountain 13 and enabling workmen to work around such conveyor withouthindrance by motors and the like located above the top of the sump 11.Further, provision of the barrier tube 27 effectively blocks moltensolder from contact with the driveshaft 23 and thereby eliminates thenormal sealing problems associated with high temperature solder of thistype.

From the foregoing it will be apparent that the soldering apparatus ofpresent invention provides an economical and convenient means formaintaining a standing solder wave above the sump structure and withoutobstruction by any drive mechanism.

Various modifications and changes may be made with regard to theforegoing detailed description without departing from the spirit of thepresent invention.

I claim:

1. Bottom drive soldering apparatus comprising:

a sump for receipt of a predetermined level of molten solder compoundand having one wall formed with a drive shaft-receiving opening disposedin the lower portion thereof;

a fountain disposed in said sump and formed in its lower portion with aninlet and including an upwardly opening horizontally extending orificedisposed at the top of said apparatus;

pump means disposed in said sump for pumping molten solder compound insaid inlet and including impeller means having drive shaft meansextending therefrom and through said opening;

driven means on the projecting extremity of said drive shaft means;

barrier tube means surrounding said drive shaft means and projectingupwardly to said predetermined level for blocking molten solder compoundfrom contacting said drive shaft means and leaking out said driveshaft-receiving opening; and

drive means coupled with said driven means for driving said impellermeans to pump molten solder compound from said sump in said inlet andupwardly in said fountain and out said orifice to form a standing wavelocated above said apparatus so work pieces to be soldered may be passedalong any horizontal path to engage said wave, and the activity ofworkmen working therewith will be unobstructed by said drive means.

2. Wave soldering apparatus as set forth in claim 1 wherein:

said barrier means includes a barrier tube telescoped over saiddriveshaft means and projecting from said opening to said pump means.

3. Wave soldering apparatus as set forth in claim 1 wherein:

said impeller means is arranged with its axis extending vertically andis formed in its center with a through vertical passage; and

said driveshaft means includes hollow drive pipe means projectingupwardly from the center of said impeller and terminating in an upperextremity disposed above said predetermined level and a driveshaftprojecting upwardly into said driveshaft pipe means; and

coupling means coupling said upper extremity of said drive pipe means tothe. upper extremity of said driveshaft.

4. Wave soldering apparatus as set forth in claim 1 wherein: a

said pump means is disposed exteriorly of said fountain and is arrangedwith the axis of said impeller 6 means extending vertically, said pumpmeans insaid shaft-receiving opening is formed in the bottom cluding ahousing formed in its top and bottom wall of said sump for and receivingsaid shaft sides with respective upper and lower inlets for remeansceiving a selected ratio of solder and oil compound for said pump meanswhereby oil compound means may be floated on said molten solder and apredetermined ratio of oil compound means will be drawn in said inletsduring operation of said pump 6. Wave soldering apparatus as set forthin claim 1 5 that includes:

bearing means interposed between said driveshaft means and said barriermeans. 7. Wave soldering apparatus as set forth in claim 3 means. 5.Wave soldering apparatus as set forth in claim 1 10 that Includes:wherein: bearing means interposed between said drlveshaft said impellermeans is arranged with its axis extendm a and aid arri r means. ingvertically;

1. Bottom drive soldering apparatus comprising: a sump for receipt of apredetermined level of molten solder compound and having one wall formedwith a drive shaftreceiving opening disposed in the lower portionthereof; a fountAin disposed in said sump and formed in its lowerportion with an inlet and including an upwardly opening horizontallyextending orifice disposed at the top of said apparatus; pump meansdisposed in said sump for pumping molten solder compound in said inletand including impeller means having drive shaft means extendingtherefrom and through said opening; driven means on the projectingextremity of said drive shaft means; barrier tube means surrounding saiddrive shaft means and projecting upwardly to said predetermined levelfor blocking molten solder compound from contacting said drive shaftmeans and leaking out said drive shaft-receiving opening; and drivemeans coupled with said driven means for driving said impeller means topump molten solder compound from said sump in said inlet and upwardly insaid fountain and out said orifice to form a standing wave located abovesaid apparatus so work pieces to be soldered may be passed along anyhorizontal path to engage said wave, and the activity of workmen workingtherewith will be unobstructed by said drive means.
 2. Wave solderingapparatus as set forth in claim 1 wherein: said barrier means includes abarrier tube telescoped over said driveshaft means and projecting fromsaid opening to said pump means.
 3. Wave soldering apparatus as setforth in claim 1 wherein: said impeller means is arranged with its axisextending vertically and is formed in its center with a through verticalpassage; and said driveshaft means includes hollow drive pipe meansprojecting upwardly from the center of said impeller and terminating inan upper extremity disposed above said predetermined level and adriveshaft projecting upwardly into said driveshaft pipe means; andcoupling means coupling said upper extremity of said drive pipe means tothe upper extremity of said driveshaft.
 4. Wave soldering apparatus asset forth in claim 1 wherein: said pump means is disposed exteriorly ofsaid fountain and is arranged with the axis of said impeller meansextending vertically, said pump means including a housing formed in itstop and bottom sides with respective upper and lower inlets forreceiving a selected ratio of solder and oil compound for said pumpmeans whereby oil compound means may be floated on said molten solderand a predetermined ratio of oil compound means will be drawn in saidinlets during operation of said pump means.
 5. Wave soldering apparatusas set forth in claim 1 wherein: said impeller means is arranged withits axis extending vertically; said shaft-receiving opening is formed inthe bottom wall of said sump for and receiving said shaft means.
 6. Wavesoldering apparatus as set forth in claim 1 that includes: bearing meansinterposed between said driveshaft means and said barrier means.
 7. Wavesoldering apparatus as set forth in claim 3 that includes: bearing meansinterposed between said driveshaft means and said barrier means.